The massive use of glass enclosures in contemporary architecture has originated large energy consumptions in buildings and an important reduction in comfort. The low thermal insulation of the glass elements combined with their uncontrolled permeability to solar radiation are the reasons for their bad energetic behavior. The worldwide trend to save energy in buildings, motivated by the energy scarcity and the contamination constraints, has triggered in recent years the development of intelligent transparent enclosures which allow to control the entrance of light and of the direct solar radiation.
As an example of these novel transparent enclosures, enclosures have been developed which increase the thermal insulation through the inclusion of layers and different materials forming a multilayer panel, as the ones described in the patents FR2828509, DE10034764, DE19829480, and DE19847634. Another type of intelligent transparent enclosures try to seek the control of illumination and thermal load by means of one or more fluids of different colors, fluids with variable transparency properties or through curtains integrated into the enclosure. The following patents are remarkable examples of this type of intelligent enclosure: U.S. Pat. No. 4,347,835, DE3716563, EP0402529, EP1367210, ES2158757, U.S. Pat. No. 4,347,835, WO200604587, DE10351023, DE3716563, DE3818543, and WO9963195. Another family of active glazings includes a circulating fluid in contact with a heat exchanger. These glazings allow the control of the thermal load and serve also as radiating surfaces for heating and cooling purposes. Examples of this family are the patents EP0075464, U.S. Pat. No. 4,515,150, DE19926343, DE4107943, and ES2180444. Last, another group of glazings achieve the illumination control by including an electrochromic layer adhered to the transparent panes. Examples of this solution are the patents DE10023765, US2005200935, WO2005076061, and US2005117193.
It is therefore desirable to have an intelligent transparent enclosure which allows the regulation of the building illumination and block or control the entrance and exit of heat through an isothermal envelope, all this done with an economic and versatile transparent system or enclosure of reduced thickness. The necessity to control the solar radiation through the convective transport in a chamber of reduced thickness requires a circulating fluid with a large thermal heat capacity, and therefore, with a large density, like a liquid.
Hence, patent DE3716563 describes a transparent enclosure with many of the sought features, where a liquid is heated by the incoming solar radiation while it crosses the interior of the enclosure. At the exit of the enclosure the liquid is driven to a heat exchanger for the evacuation of the absorbed heat and thereafter returned to the enclosure. The so formed closed circuit is kept in motion by using a circulation pump.
But the presence of the liquid in the interior of the enclosure leads to significant hydrostatic pressures which require the use of transparent panes with large thicknesses in order to avoid their breakage. This problem is present in all the cited patents in which one or several liquids are in between the two transparent panes, making the realization of these inventions economically enviable in the formats and sizes common in architecture.
The present invention differs from the cited patents in that in reduces the hydrostatic pressure supported by the transparent panes and induced by the liquid in the closed circuit. The reduction of the supported hydrostatic pressure, and therefore of the required thicknesses of the transparent panes, allows the consecution of an economical intelligent enclosure system with luminic and calorific energy management capabilities.
Other technological solutions exist which allow the construction of transparent enclosures in formats and sizes common in architecture. The patent considered most close to the actual state of the art is FR2176916. In this patent the hydrostatic pressure problem is solved by imposing the atmospheric pressure at the bottom of the enclosure, so that the glass panes are exposed to a depression instead of an overpressure. In order to avoid the breaking of the panes, the patent introduces spacers between the panes to keep them in place and hence reduce their effective span. The main difference with the present invention is that the latter sets the atmospheric pressure at the vertical center of the enclosure. In this way the panes are exposed to depression in their upper half part and to overpressure in their bottom half part, leading to a zero resulting force. The consequence of this subtle, but transcendental change is a radically different load state of the panes, leading to much smaller deflections, and therefore stresses. The absence of spacers to solve the problem induced by the hydrostatic pressure represents an important technological advantage in economic, constructive, manufacturing and esthetic terms.
The invention described in the present patent has four fundamental advantages compared to the similar inventions described before. First, it allows the blockage of an important part of the incoming radiation energy and its transfer to another system, avoiding the temperature increase inside the building. Second advantage is the hydrostatic pressure reducer device which allows the use of reduced thicknesses in the panes that contain the liquid, and with it the cost, weight, and complexity of the enclosure. The third advantage is an energetic one, as the energy requirements for climatization of the interior of the building are significantly reduced, leading to savings in cooling and heating. Fourth advantage is the modular design, which allows an independent manufacture and ensures a maintainability of the system: the breaking of one module does not imply the failing of the complete system, and the repairing can be performed independently without affecting the working of the rest of the system.